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JOURNALS // Trudy Matematicheskogo Instituta imeni V.A. Steklova // Archive

Trudy Mat. Inst. Steklova, 2021 Volume 312, Pages 224–235 (Mi tm4136)

This article is cited in 1 paper

Kolmogorov Widths of the Besov Classes $B^1_{1,\theta }$ and Products of Octahedra

Yuri V. Malykhinab

a Steklov Mathematical Institute of Russian Academy of Sciences, ul. Gubkina 8, Moscow, 119991 Russia
b Laboratory “High-Dimensional Approximation and Applications,” Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119991 Russia

Abstract: We find the decay orders of the Kolmogorov widths of some Besov classes related to $W^1_1$ (the behavior of the widths for the class $W^1_1$ remains unknown): $d_n(B^1_{1,\theta }[0,1],L_q[0,1])\asymp n^{-1/2}\log ^{\max \{1/2,1-1/\theta \}}n$ for $2<q<\infty $ and $1\le \theta \le \infty $. The proof relies on the lower bound for the width of a product of octahedra in a special norm (maximum of two weighted $\ell _{q_i}$ norms). This bound generalizes B. S. Kashin's theorem on the widths of octahedra in $\ell _q$.

UDC: 517.518

Received: May 19, 2020
Revised: October 10, 2020
Accepted: October 20, 2020

DOI: 10.4213/tm4136


 English version:
Proceedings of the Steklov Institute of Mathematics, 2021, 312, 215–225

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